1. Field of the Invention
This invention relates to novel polymer/polyol compositions which can react with polyisocyanates to form polyurethane products. The invention also relates to a novel method for making such compositions, and to novel polyurethane products, including tolylene diisocyanate based high resilience ("HR") foams made from such polymer/polyol compositions.
2. Description of the Prior Art
Polymer/polyol compositions suitable for use in producing polyurethane foams, elastomers, and the like, are known materials. The basic patents in this field are U.S. Pat. No. 3,304,273, 3,383,351, Re. 28,715 and Re. 29,118 to Stamberger. Such compositions can be produced by polymerizing one or more olefinically unsaturated monomers dissolved or dispersed in a polyol in the presence of a free radical catalyst. Polymer/polyol compositions have the valuable property of imparting to, for example, polyurethane foams and elastomers produced therefrom, higher load-bearing properties than are provided by unmodified polyols.
Polymer/polyols containing vinylidene chloride have been disclosed previously. For example, Dewald (U.S. Pat. No. 3,655,553) describes the preparation of polymer/polyols containing vinylidene chloride (but no acrylonitrile) in a polyol or a polyol blend. He employed a low reaction temperature (65.degree. C.) and a semi-batch process. Another example is the Patton et al. (U.S. Pat. No. 3,875,258) disclosure of polymer/polyols containing copolymers of bis(.beta.-chloroethyl) vinyl phosphonate and vinylidene chloride and also polymer/polyols containing copolymers of bis(.beta.-chloroethyl) vinyl phosphonate, styrene, and vinylidene chloride. They employ a high reaction temperature (125.degree.-130.degree. C.) and a semi-batch process. Both Dewald and Patton et al. teach that such polymer/polyols can be utilized in the preparation of polyurethanes having flame retardant properties.
A Ramlow et al. patent (U.S. Pat. No. 3,953,393) teaches the preparation of polymer/polyols containing vinylidene chloride only or copolymers of vinylidene chloride and vinyl acetate or ethyl acrylate or methyl methacrylate in polyols containing added unsaturation. It operates at a temperature below 100.degree. C., in the presence of a free-radical catalyst and a chain transfer agent (such as dodecylmercaptan). It employs a batch process having a typical holding time of 4 to 6 hours. According to its teachings, high reaction temperatures (i.e. greater than 100.degree. C.) do considerable damage to sensitive monomers such as acrylonitrile and vinylidene chloride as well as to the polyols, resulting in colored dispersions. Kuryla (Canadian Pat. No. 735,010) provides a generic teaching of the preparation of polyurethane foams from isocyanates and polymer/polyol compositions. The generic teachings of Kuryla relate to polyols having hydroxyl numbers of at least about 40. Among the monomers listed by Kuryla are acrylonitrile and vinylidene chloride. Examples 17 and 18 of Kuryla describe polymer/polyol compositions made with mixtures of acrylonitrile and vinylidene chloride (which are used to make polyurethane foams in Examples 64 and 65). However, Kuryla employs 50 percent or more vinylidene chloride in the monomer mixture, which results in a high degree of dehydrochlorination. Kuryla prepares the polymer/polyol compositions in a semi-batch process employing peroxide catalysts at low reaction temperatures (60.degree.-87.degree. C.) with a reaction period of 8-9 hours, which likewise significantly increases the degree of dehydrochlorination. Neither Ramlow et al. nor Kuryla contains a teaching that fire retardant polyurethanes products can be made from the polymer/polyol compositions which they disclose.
Current commercial molded high resilience (HR) foams are based, in many cases, upon an isocyanate blend (of tolylene diisocyanates and a polymeric isocyanate) and a polymer/polyol composition derived from acrylonitrile and styrene. A continuous process for the production of acrylonitrile:styrene-polymer/polyol is described in Priest (British Patent Specification No. 1,412,797--Example 7). As far as is known, none of the above-mentioned vinylidene chloride-polymer/polyols have been used commercially in producing molded HR foams. As discussed in the copending Seefried et al. U.S. Pat. application cross-referenced supra, there are substantial industry incentives to base molded HR foams on a single isocyanate. In producing molded HR foams from tolylene diisocyanate alone, small concentrations of additive flame retardants are required to enable the foams to meet Federal Motor Vehicle Safety Standard (FMVSS) No. 302 specifications. Generally, flame retardant additives are not stable in resin premixes and must be metered in a separate stream to the foam machine mixing head. Elimination of the special equipment and handling procedures for the additive flame retardant would significantly simplify the foam production operation.
Seefried et al. disclose molded, high resilience, flexible urethane foams produced from tolylene diisocyanate and a polymer/polyol in which the polymer is made from a minor amount of acrylonitrile and a major amount of vinylidene chloride. The Application teaches that such foams have desirable load-bearing characteristics and exhibit fire retardant properties which obviate the necessity for fire retardant additives. The polymer/polyol compositions used to prepare the Seefried et al. foams are prepared by a method generally similar to that of Kuryla, although the polyols utilized in the Seefried et al. Application are ethylene oxide-capped and have very low hydroxyl numbers. Accordingly, the Seefried et al. foams are, unlike those of Kuryla, high resilience foams.